#define _CRT_SECURE_NO_WARNINGS 1
class Solution {
public:
    int singleNumber(vector<int>& nums) {
        int ret = 0;
        for (int i = 0; i < 32; i++) {
            int sum = 0;
            for (auto e : nums) {
                if (((e >> i) & 1) == 1)
                    sum++;
            }
            sum %= 3;
            if (sum == 1)
                ret |= 1 << i;

        }
        return ret;
    }
};